The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Vic budget $40m cut to CFA: Labor

Victoria's mostly volunteer Country Fire Authority is facing a $40 million budget cut next week, the state opposition claims.

Opposition spokeswoman for emergency services and bushfire response, Jacinta Allan, says leaked documents obtained by Labor show that local CFA group officers were briefed by CFA command on the Victorian government's plans.

Ms Allan has called on Premier Denis Napthine to confirm or deny the massive cut ahead of next week's state budget.

She said the CFA was already struggling under the pressures of last year's $41 million budget cuts, on top of a broken election commitment of $136 million for support and training of the state's fire services.

She said the CFA battled through this year's bushfire season with a shortage of uniforms, trucks and ration packs and a spate of technological failures.

"Further budget cuts by the Napthine government will have disastrous implications on bushfire preparedness and the government's ability to implement key recommendations of the bushfire royal commission, which they committed to implement 'lock, stock and barrel'," Ms Allan said.

"If these budget cuts exist, Denis Napthine must come clean and provide a full explanation why an additional $40 million will be cut from the Country Fire Authority."